Expose SIMD.Float32x4 type to Javascript.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index f272aa501015889098573bf79142de6dd9a1e7c7..d6293f320474e1f04435cf48820989287df6f178 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -81,6 +81,8 @@ MaybeHandle<JSReceiver> Object::ToObject(Isolate* isolate,
     constructor = handle(native_context->string_function(), isolate);
   } else if (object->IsSymbol()) {
     constructor = handle(native_context->symbol_function(), isolate);
+  } else if (object->IsFloat32x4()) {
+    constructor = handle(native_context->float32x4_function(), isolate);
   } else {
     return MaybeHandle<JSReceiver>();
   }
@@ -610,7 +612,7 @@ Map* Object::GetRootMap(Isolate* isolate) {
 
   HeapObject* heap_object = HeapObject::cast(this);
 
-  // The object is either a number, a string, a boolean,
+  // The object is either a number, a string, a symbol, a boolean, a SIMD value,
   // a real JS object, or a Harmony proxy.
   if (heap_object->IsJSReceiver()) {
     return heap_object->map();
@@ -629,6 +631,9 @@ Map* Object::GetRootMap(Isolate* isolate) {
   if (heap_object->IsBoolean()) {
     return context->boolean_function()->initial_map();
   }
+  if (heap_object->IsFloat32x4()) {
+    return context->float32x4_function()->initial_map();
+  }
   return isolate->heap()->null_value()->map();
 }